Explosive ammunition and a method of manufacturing the same



Julie 14, 1960 L. o. BERGSTROM ET AL ,9

EXPLOSIVE AMMUNITION AND A METHOD OF MANUFACTURING THE SAME Filed Jan. 5, 1957 2 Sheets-Sheet 1' Y I N VENTORS Lms 08cm? .Bskssrn'n JPN/v5 OAOF P5855 on/ June 14, 1960 L. o. BERGSTRGM ET AL 3 3 EXPLOSIVE AMMUNITION AND A METHOD OF MANUFACTURING THE SAME Filed Jan. 3, 1957 2 Sheets-Sheet 2 EXPLOSIVE AMIVIUNITION AND A METHOD OF MANUFACTURING THE SAME Lars Oscar Bergstriim, Bofors, and Janne Olof Persson, Karlskoga, Sweden, assignors to Aktiebolaget Bofors, Bofors, Sweden, a corporation of Sweden Filed Jan. 3, 1957, Ser. No. 632,333

. Claims prority, application Sweden Jan. 11, 1956 4 Claims. (Cl. 102-8) The present invention relates to explosive ammunition and a method of manufacturing the same.

The term ammumtion as herein used, is intended toencompass stationary ammunition, for instance land,

mines such as anti-tank mines and also ballistic missiles such as shells, thewarheads of rockets, etc.

Land minds such as anti-tank mines the explosive mait .was found that the keen sense of smell of trained dogs '7 can easily locate the mines by the odor of the plastic casings- An attempt has been made to eliminate entirely the use of a special casing by casting explosive material in the appropriate shape. Such mines cannot be easily detected either by mine detectors or dogs, but it was found that the mechanical strength of the cast explosive material is inherently too low for the purpose. Attempts "have been made to reinforce the minebody by mixing 7 fibre material of suitable length in the liquefied explosive material. However, these attempts have failed as' the fibre material tends to bunch so that the hardened mine body lacks reasonable uniform strength. i -..Accordingly, one of the objects of the present invention is to provide a novel and improved ammunition of :the land mine type which when concealed cannot be detected by detectors responsive to metal or by the odor .of. its casing yet possesses a strength fully adequatefor the purpose. F V

Another object of the invention is to provide a novel and improved piece of ammunition which utilizes as a casing a special re-enforced layer which is formed out of the explosive material and hence participates in the explosive effect thereby amplifying same.

Still another object of the invention is to provide a novel and improved casing made of explosive material and of considerable strength which casing is suitable for use as -a shell casing, a casing for the war head of a rocket,- a casing for a land mine etc., and which if used as the casing for a land mine affords the specific advantage of defying detection by its odor. 7

A further object of the invention, allied with the preceding ones, is to provide a novel and improved method of manufacturing ammunition of the general kind above referred to.

A still further object of the invention is to provide a novel and improved method of manufacturing ammunition in which liquefied but hardening explosive material is layered, the outermost layer being reinforced and constituting the casing of the ammunition.

Yet a further object of the invention is to provide a 2,940,390 Patented June 14,1960

ie a

novel and improved method of producing ammunition of the general kind abovereferred to, by casting one or several layers of the same or different explosive material within a hollow mold from which the finished ammunition can be conveniently removed.

Other further objects, features and advantages of the invention will be pointed out hereinafter and set forth in the appended claims forming part of the application.

In the accompanying drawing several preferred embodiments of the invention are shown by way of illustration and not byway of limitation.

In the drawing: v V Fig. 1 is a sectional view of a mold for manufacturing a land mine according to the invention, the method of manufacture being shown in an initial stage.

Fig. 2 is a sectional view similar to Fig. 1,, but showing a more advanced stage of the manufacture.

Fig. 3 is a sectionalperspective view of the mold and Fig. 4 is a perspective sectional view of a mold designeda for producing a casing according to the invention for a shell, and

Fig. 5 is a sectional view of a completedshell casing according to the invention while being removed from.

the mold.

Referring first to Figs. 1, 2 and 3 in detail, the exemplification of the invention according to these figures, shows two halves 1 and 2. of a mold for manufacturing the casing for a land mine. One or several protrusions or inserts may be providedwithin the mold to serve as mounting lugs for parts which have to be fitted in the body of the casing or the finished mine. The half 1 of the mold shown as the upper part thereof is. formed with an aperture! in which is fitted an internally threaded cup or sleeve 4 intended to protrude into the body of the casing. Sleeve or cup 4 may be used to receive the firing mechanism of the mine or a part of the mechanism. The mold cavity defines the usual, generally oval or lentil shape and has at diametrically opposite points of its peripheral rim two apertures inwhich plugs 5 and 6 are threaded. The apertures for the plugs, when the same are removed, serve as air vent andfilling openings respectively. Aperture 3 may also be used for this purpose.

In the first stage of manufacture, the cavity of the mold is lined with a fibrous layer 7 in amanner such that the material of the layer forms in 'eifect a more or less coherent fabric. The layer material should be such that mine detectors do not respond thereto. 1 Glass wool has been found suitable for the purpose. Afterthe for mation of layer 7, the cavity'is filledwith a liquefied,

buthardening explosive material 8. This explosiveis poured into :the mold through one or two of the openings therein, one of the openings being reserved as an air vent. In the event opening 3 is utilized as a filling opening, sleeve or 'cup 4- is subsequently inserted. The filled-in explosive will begin to harden from its outside surface toward its interior and after an appropriate length of time, depending upon the characteristics of the explosive employed, a sufficient quantity of the explosive will have hardened to form a wall of appropriate thickness. Plugs 5 and 6 which have been reinserted upon completion-of the filling operation are now removed and the part of the explosive still liquefied is poured out as shown in Fig. 2, leaving in the mold a casing of the desired wall thickness and reinforced by the fiber material embedded therein. The mold is thereupon refilled either with the same explosive or with another suitable liquid explosive. After the second filling has hardened enough to form a second layer usually adhesive to the first layer, the remaining still liquefied explosives is poured out. In

'the wall of which is formed is inserted in the mold cavity through bore "3, ftube can be rotated by suitable drive means and also be moved up and down within themold havity. It should ;bevisu,alized as being connectedtofasupplybf suitable this manner any desired number of layers may be cast.

However, in many cases, it has been found that-a casing,

of a single layer, is sufiicient for the purpose. I e I The remaining final cavity within thecasing is thereupon fille'd-thr'c'iugh one of the openings with a desired explosive material. It has been found that suitable explo- "sives for casting the casing proper'areexplosives such as T.N.T., tritonal, torpex and cyclotoli a As is apparent from the previous description, the liquefied explosive material forming the first layer will "penetrate into the interstices of the fiber material forming layer 7 thereby binding with the fibres and' becoming =reinforced by'the' same. Fig. 3 shows the casing ready to be filled with the additional explosive. r j I Referring now to Figs. 4 and 5, the mold; according to fthese 'figures is designed, as 'previously me'ntio-ned, to V produce the casingo'f a'sh'ell of'conventionalconfiguratube and the mold. Similarly, the mold of Figs. lto

3 may be partly filled only and rotated about an appropriate axis to distribute the liquefied explosive material tion, The mold comprises'two halves l and z' which may be joined to each joth'e'r by-a conventional screw joint. The upper half ll of th'eflnzioldio'r fojrm-ingtlie 'Tn'ose end of the shell casing has an axial bore :3", in -which e sleeve 4' can befitted to form a'housingfor the ee lower half 2"oi'the mold alsoihas an axial' bore '5" for receiving a sleeve that is intended to extend inthe body, of the'finishe d shell casing. Sleeve 6 serves to house an other part of thejfiring mechanism.

In the first staged-manufacture, the-inner wall of the mold is lined with a reinforcement layer 7 inthe form 'of a fabri'cjlay er. Layer 7'-may be made of glass'woo-l or of metal especially metalithr'eads sincefthe problem of detection is not present with shell casings.

In the next stage of production a hollow feed tube 9 This liquefied explosive material. To cast the casing of the "shellin accordance with the invention; tube 9 is lowered within the mold to a point fat waiters mouth is'close fto the bottom'of the mold then rotated'while being ,slowlyraised. Asa result, the liquid explosivernaterial "which leaves thetube through the bottom and 7 or lateral openings thereof is thrown bythe centrifugal force against the wall of the mold cavity andmorespecifically"upon the layer 1', lining 'the same, As is evident, the explosive material'when hardening will form a coating along the inner wall of the mold and penetrate into the interstices of the material'jorming liner'7; 'The thickness of the r coating can-beconveniently controlled by -the speed at which tube 9 is raisedwithin the mold. After the coating "is hardened, any number of additional coatings may be formed'in the 'same mannen either of the sameexplosive' material oria difierent one depending upon the specific requirements. ,The remaining final cavity is then-filled Withasuitable.explosive rnaterial in the same manner as the conventional casing of ashell. r

other, kinds; of ammunition having a rotation symmetric configuration as shown in Figs. 4 and,5 canibe produced in the same manner, that'is, by distributing the explosive material upon a reinforcement layer lining the mold cavity by spinning the feed ,tube 9. in-this connection, it may be mentioned-thatthe same eifect as is obtained,

in'Figs, 4"and 5 by rotating; tube 9, can also lie-procured by rotating the mold proper, or rotatingboth the. feed Asis obvious from the previous description, casings for" layer.

over fiber lining 7.

Tests have shown that casings, according to the invention, that is, casings having awall made of explosive material including uniformly distributedreinforcement material, possess a .veryrconsiderable strength. It has been found that casings for land mines are capable of withstanding a load of about.2,0,00 kg. when the cavity of the casing is filled with explosive material.

While the invention has been described in detail with 'respecttocertain now preferred examples and embodiments of the invention it will'be understood by those skilled in the art'after understanding the "invention that various changes and modifications may bemade without departing from the spirit and scope of the invention, and it is intended, therefore, to' cover all such changes and modifications .in theappended claims.

"What is claimed as newzand desired'to be'securedby Lettersf'Pa'tent, is: A I r i l. A self contained explosive land mine comprising, in combination, an external reinforcing layer, a plurality of discrete internal cast layers ofhardened explosive material .en-ve'loped by said external reinforcing layer,ysaid "external reinforcing layerincluding a fabric'skeleton of inter-meshing fibrous material embedded in the outermost one of said internal cast layers, the explosive material-0f said'outermost internal cast layer penetrating into the interstices of said fibrous material bonding said external reinforcing layer to said outermost internal cast v2. A casing according to claim "1, wherein said fabric is made of glass wool. f x r 3. A casing according to claim 1, wherein saidfabricis made of metal threads. e

4. A method of producing ammunition of the kind described, comprising the steps of lining a mold cavity defining the outer configuration of a casing with a'layer of fibrous intermeshing material, inserting in the mold cavity a'feeder tube for feeding hardening liquefied explosive material'into the lined cavity, displacing 'thedischarge end of said tube axially within the mold cavity between the top and the bottom thereof and simultaneously rotating the mold and the tube relative to the mold'abou't its-longitudinal axis, whereby the explosive material is e i applied by centrifugal force to said fibrous linerpenctra'te ing into the interstices thereof, allowing time for harden? ing of the explosive material filling said interstices," removing still liquid explosive material" whereby theremaining hardened explosive material constitutes a casing reinforced by thefibrous material embedded therein, and

filling the interior. of ,said casing with explosive material.

7 References Cited in the file of this patent UNITED STATES PATENTS v1,301,380 I Buckingham Apr. 2 2, 1919, 

1. A SELF CONTAINED EXPLOSIVE LAND MINE COMPRISING, IN COMBINATION, AN EXTERNAL REINFORCING LAYER, A PLURALITY OF DISCRETE INTERNAL CAST LAYERS HARDNED EXPLOSIVE MATERIAL ENVELOPED BY SAID EXTERNAL REINFORCING LAYER, SAID EXTERNAL REINFORCING LAYER INCLUDING A FABRIC SKELETON OF INTER-MESHING FIBROUS MATERIAL EMBEDDED IN THE OUTERMOST ONE OF SAID INTERNAL CAST LAYERS THE EXPLOSIVE MATERIAL OF SAID OUTERMOST INTERNAL CAST LAYER PENETRATING INTO THE 